In many types of electrical equipment, low-voltage controlled relays are required to switch heavy load current. If, in such applications, the control circuit is designed to be implemented on a printed circuit board (PCB), a relay with PCB terminal pins must be used. However, for thermal reasons, PCB conductor paths are not capable of conducting heavy load current over long distances. Consequently, such PCB relays are provided with additional quick-connect terminals that have greater cross-sections than the PCB conductor paths to conduct the load current away from the PCB circuit.
A relay specifically designed to accomplish this purpose is described in U.S. Pat. No. 4,602,230. The described relay has contact rails extending from a side wall of the relay housing that provide downward-facing soldering pins and upward-facing quick-connect terminals. The use of the described contact rails, however, considerably increases the overall basal plane of the relay on the PCB (i.e. the "footprint" or the area of PCB surface occupied by the relay mounted thereon). Thus, the relay fails to conserve scarce (and, thus, valuable) board space, which is a standard design goal for PCB components.
In another known relay, described in European Patent Application EP-A-O 409 613, contact elements contained within the relay housing form soldering pins extending downward through a bottom wall as well as quick-connect terminals extending upward through a top wall of the housing. Disadvantageously, this arrangement requires the use of a specific relay and contact structure, i.e., it cannot be adapted for use by an existing PCB relay. Further, the described arrangement requires an increased total volume of the relay housing in order to provide sufficient space for the quick-connect terminals as well as the necessary insulation dimensions. Further, in both known relays, additional openings in the relay housing to accommodate quick-connect terminals render sealing of the housing more difficult and more costly.
It is therefore an object of the present invention to provide a PCB relay having an improved terminal structure allowing heavy load currents to be conducted away from a PCB by quick-connect terminals.
It is a further object of the present invention to provide quick-connect terminals on a PCB relay with little expenditure of cost and PCB space.
It is a still further object of the present invention to provide quick-connect terminals on a PCB relay without affecting the internal structure of the relay.
It is a still further object of the present invention to provide a quick-connect terminal structure which can be supplemented to an existing PCB relay simply by modifying a relay housing or cover without changing the internal relay and contact structure.